Lab tech tooking into a microscope. She is wearing PPE and a white lab coat

HIV-1 Genotypic Testing

Genotypic testing isolates amino acid sequences of viral proteins and analyzes for the presence of mutations associated with antiretroviral (ARV) resistance. A rules-based algorithm is utilized to make predictions of ARV susceptibility based on the presence of mutations in the patient viral population.

supporting image

The Department of Health and Human Services (DHHS) Guidelines recommend genotypic testing at baseline and at first and second treatment failures in patients with suboptimal response or virologic failure.1

Labcorp offers several genotypic testing options for a combination of HIV-1 ARV classes, as well as targeted testing for integrase inhibitors.

Genotypic testing provides a three tiered assessment of drug susceptibility:

  • Sensitive
  • Resistance possible
  • Resistant

Genotypic testing options

All genotypic assays require a viral load of > 500 copies/mL with the exception of GenoSure Archive®, which was designed for use in patients with non-detectable viral loads or low level viremia. 

If genotypic testing fails on the initial attempt to result, the laboratory will perform in-house viral load testing to confirm adequate viral material. If the viral load is < 500 copies/mL, the viral load will be reported and the client will be billed for viral load testing. 

If a patient’s viral load varies around the 500 copies/mL viral load requirement, it is possible to order viral load reflex testing (550920) in which a viral load reflexes to either GenoSure PRIme® or GenoSure Archive®. 

  • If the viral load is > 500 copies/mL, testing will reflex to GenoSure PRIme®
  • If the viral load is < 500 copies/mL, testing will reflex to GenoSure Archive®

Viral load reflex testing is also available for GenoSure® MG and GenoSure PRIme®.